Cores on which are rolled sheet materials, as for example a metal sheet or an expanded metal sheet are typically formed from cardboard. Cardboard cores are not reusable as they are effected by their surrounding environment. Moisture quickly subjects cardboard cores to water damage. Other environmental factors may also cause a cardboard core to fail or delaminate. Tension applied to the sheet of material when being wrapped on a cardboard core may also subjects a cardboard core to delamination. Thus cardboard cores are made to be disposable and not re-useable. In addition, in order to increase strength, cardboard cores are made thicker (having thicker walls). As a result, they tend to be heavier, have a larger outer diameter and thus allow for less sheet material to be wrapped around them when the outer diameter of the core with the wrapped material has to be limited for shipping and storage purposes.